HISTORY  OF  PETROLEUM  OR  ROCK  OIL. 
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considerable  depth  in  the  rock  have  yielded  an  oil  still  thinner, 
lighter  colored,  and  less  dense,  which  is  prized  as  being  more 
profitable  for  refining.  The  present  wholesale  price  of  the 
crude  oil  from  Kelly's  wells,  delivered  at  Wyoming  station  on 
the  Grand  Trunk  Railway,  is  about  thirteen  cents  a  gallon. 
The  oil  obtained  by  Mr.  Williams  is  refined  in  Hamilton,  while 
that  from  the  northern  part  of  the  township  has  hitherto  been 
sent  to  Boston,  though  refining  works  are  now  being  erected  at 
the  wells.  The  process  of  refining  consists  in  rectifying  by  re- 
peated distillations,  by  which  the  oil  is  separated  into  a  heavier 
part  employed  for  lubricating  machinery,  and  a  lighter  oil, 
which,  after  being  purified  and  deodorised  by  a  peculiar  treat- 
ment with  sulphuric  acid,  is  fit  for  burning  in  lamps. 
These  wells  occur  along  the  line  of  a  low,  broad  anticlinal 
axis,  which  runs  nearly  east  and  west  through  the  Western 
Peninsula  of  Canada,  and  brings  to  the  surface  in  Enniskillen 
the  shales  and  limestones  of  the  Hamilton  group,  which  are 
there  covered  with  a  few  feet  of  clay.  The  oil  doubtless  rises 
from  the  Corniferous  limestone,  which,  as  we  have  seen,  con- 
tains petroleum.  This  being  lighter  than  the  water  which  per- 
meates at  the  same  time  the  porous  strata,  rises  to  the  higher 
portion  of  the  formation,  which  is  the  crest  of  the  anticlinal 
axis,  where  the  petroleum  of  a  considerable  area  accumulates, 
and  slowly  finds  its  way  to  the  surface  through  vertical  fissures 
in  the  overlying  Hamilton  shales,  giving  rise  to  the  oil  springs 
of  the  region.  The  oil  is  met  with  at  various  depths.  In  some 
cases  an  abundant  supply  is  obtained  at  forty  feet,  while  near 
by  it  is  only  met  with  at  three  or  four  times  that  depth,  and 
sometimes  only  in  small  quantities.  Everything  points  to  the 
existence  of  separate  fissures  communicating  with  a  deep-seated 
source.  At  Kelly's  wells,  however,  it  would  appear  that  a  re- 
servoir has  been  formed  much  nearer  the  surface,  where  in  a 
bed  of  gravel  and  boulders,  underlying  the  superficial  clays,  the 
oil  rising  from  the  rocks  beneath  has  accumulated.  The  inflam. 
mable  gas  which  issues  from  the  wells  is  not  necessarily  con- 
nected with  the  petroleum,  inasmuch  as  it  is  an  almost  con- 
stant product  of  the  decomposition  of  organic  matters,  and  is 
copiously  evolved  from  rocks  which  are  destitute  of  bitumen. 
It  is  similar  to  the  gas  of  marshes  and  to  the  fire-damp  of  coal 
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